Colored or diffusing coating for incandescent lamps and similar articles



March 19, 1929. M. PIPKIN 1,706,182

COLORED OR DIFFUSING COATING FOR INCANDESCENT LAMPS AND STMILAR ARTICLES Filed Sept. 20, 1926 WE R'SZJJV FJPKZN,

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Patented Mar. 19, 1929.

UNITED STATES REISSUED 1.1oa1s2 PATENT OFFICE.

MARVIN PIPKIN, OE CLEVELAND HEIGHTS, OHIO, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

COLORED OR DIFFUSING COATING FOR INOANDESCENT LAMPS AND SIMILAR ARTICLES.

Application filed September 20, 1926. Serial No. 136,393.

My invention relates to the application of a light diffusing or coloring medium to electric incandescent lamp bulbs and similar articles. Heretofore this has been done by applying such medium to the outer surface of a clear glass bulb. This method has the disadvantage that it increases considerably the absorption of light inasmuch as the highly reflective inner surface of the bulb remains. The outside coated lamps have also the disadvantages that dirt adheres more easily to them. I

It is the object of my invention to overcome these various objections and this I do by applying the light diffusing or coloring medium to the inside surface of the bulb. Moreover, I apply said medium to the etched inner surface of the bulb and preferably to the inner bulb surface frosted by etching as by the method disclosed in Pipkin Patent N 0. 1,687,510, issued October 16, 1928. i This has the advantage that the rough etched surface serves to hold the medium to the glass, and I have found that it is unnecessary to employ a special adhesive or binding medium.

My invention may be more fully understood by referring to the accompanying drawing in which Fig. 1 is an elevation of an incandescent lamp bulb partially broken away for clearness; Fig. 2 is a fragmentary elevation of an incandescent lamp bulb partially broken away in order that a color applying means may be shown inserted therein; Fig. 3 is a fragmentary elevation of an apparatus which may be used in carrying out a modified method; and Fig. 4 is an elevation of a completed lamp partially broken away showing a series of lines which indicate the color on the inner surface thereof.

Referring now to the drawings, and especially Fig. 1, an incandescent lamp bulb 10 is shown having its inside surface 11 frosted according to the method set forth in my To apply a color or tint, a quantity of dry powdered pigment 12 of the desired color may be introduced into the bulb and allowed to deposit over the glass surface by moving and turning the bulb so that color may be uniformly distributed. A cork or stopper 13 is inserted into the neck of the bulb so as to prevent the escape of the powdered. pigment during the coloring operation. After the bulb has been properly colored or tinted, the excess pigment powder is transferred to another bulb for coloring and, if necessary, any loose pigment remaining in the colored bulb may be blown out by the use of compressed air.

In Fig. 2 is shown another ing the dry pigment owder to the inside surface of the bulb. his is by means of a brush 14, the lower end 15 of which is supplied with a quantity of dry pigment. It will be obvious that a mechanically driven bufier could be used in place of the manually operated brush.

The coloring material used should be of such a character that it will not give off gases injurious to the lamp filament at lamp operating temperature. I have obtained good results by using ceramic pigments, especially mineral colors which remain permanent and do not affect the life or efficiency of the lamps. Examples are the various pigments, principally metallic oxides, sulphides, and silicates used in the paint and glass industries. Of course the pigment used depends upon the color desired. For instance, for so-called flame-tint lamps, I have successfully used a pigment known commercially as transparent red No. 17 6 put out by B. F. Drakenfelt & Company, Inc. for ink bulbs, a pigment known as red No. 12,5 7 put out by The O. Hommel Company; for orange bulbs, a lead chromate known as C. P. Orange chrome yellow put out by Tock Brothers; for green or blue, mineral colors known as emerald green, 788 D, and blue No. 6990 O. G. put out by Roessler and Hasslacher Company; and for an opal finish, I use either barium sulphate or ground natural cryolite.

Another method of applying a light diffusing or coloring medium to the inside surface of a glass article is-by flushing or spraying the inside frosted surface of the glass article with a liquid or solution containing the desired color. A solution is used containing a compound or compounds in solution or suspension which will, when dry, or upon the application of heat, break up into a substance which has the desired color. Solutions which have been found suitable are ferric chloride in solution or ferric way of applyhydroxide in suspension, also chromic chlorlde in solution or chromic hydroxide in suspension in water or other carrying liquid.

In Fig. 3 is shown an apparatus for a plying the coloring solution to the insi e frosted surface of a glass article, and comprises a reservoir 16 containing the coloring solution 17. 'A suitable holder 18 is provided which serves to support the glass article which, as shown, is an incandescent lamp bulb 19. The coloring solution is forced up through a pipe 20 to the inside of the lamp bulb by air pressure applied through a pipe 21. The surplus coloring solution returns to the reservoir through the funnel 22 and pipe 23. After the inside surface of the bulb has been thoroughly washed with the coloring solution, the bulb is allowed to drain and when comparatively dry, it is heated in an oven at a suitable temperature until the desired color is imparted thereto. In Fig. 4 is shown a completed electric incandescent lamp, the bulb of which is partially broken away so as to show the inside surface 24 which is colored.

\Vhat I claim as new and desire to. secure by Letters Patent of the United States, is

1. The method of producing difiusing or colored bulbs for electric incandescent lamps and similar articles which consists in etching a surface thereof and then applying thereto a diffusing or coloring medium so as to produce a deposit of the finely divided medium in the depressions of said etched surface to serve without additional binding medium as the finished coating.

2. The method of producing diffusing or colored bulbs for electric incandescent lamps and similar articles which consists in etching a surface thereof andthen rubbing a finely divided diffusing or coloring medium into said etched surface.

3. The method of producing diffusing or colored bulbs for electric incandescent lamps and similar articles which consists in frosting by etching a surface thereof, and then applying thereto a diffusing or coloring medium so as to produce a deposit of the finely divided medium in the depression of said frosted surface to serve without additional binding medium as the finished coating.

4. The method of producing diffusing or colored bulbs for electric incandescent lamps and similar articles which consists in frosting by etching a surface thereof, and then rubbing a finely divided diffusing or colored medium into said frosted surface.

5. The method of producing diffusing or colored bulbs for electric incandescent lamps and similar articles which consists in etching the inside surface thereof, and then applying thereto a diffusing or coloring medium so as to produce a deposit of the finely divided medium in the depressions of said etched surface to serve without additional binding medium as the finished coating.

6. The method of producing diffusing or colored bulbs for electric incandescent lamps and similar articles which consists in etching the inside surface thereof, and then rubbing a finely divided diffusing or coloring medium into said etched surface.

7. The method of producing diffusing or colored bulbs for electric incandescent lamps and similar articles which consists in frosting by etching the inside surface thereof, and then applying thereto a diffusing or coloring medium so as to produce a deposit of the finely divided medium in the depressions of said frosted surface to serve without additional binding medium as the finished coating.

8. The method of producing diffusing or colored bulbs for electric incandescent lamps and similar articleswhich consists in frosting by etching the inside surface thereof, and then rubbing'a finely divided diffusing or coloring medium into said frosted surface.

9. A lamp comprising a glass bulb having a surface thereof etched and then coated with a finely divided diffusing or coloring medium deposited in the depressions of said etched surface and serving without additional binding medium as the finished coating.

10. A lamp comprisig a glass bulb having a surface thereof. etched and then coated with a finely divided mineral diffusing or coloring medium deposited in the depressions of said etched surface and serving without additional binding medium as the finished .coating.

11. A lamp comprising a glass bulb having the inside surface thereof etched and then coated with a finely divided diffusing or coloring medium deposited in the depressions of said etched surface and serving without additional binding medium as the finished coating.

12. A lamp comprising a glass bulb having the inside surface thereof etched and then coated with a. finely divided mineral diffusing or coloring medium deposited in .the depressions of said etched surface and serving Without additional' binding medium as the finished coating.

13. The method of producing diffusing or colored bulbs for electric incandescentlamps and similar articles which consists in introducing into a bulb which has been frosted MARVIN PIPKIN. 

